[BUGS]org.springframework.validation.BindException

错误信息：

org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 2 errors
Field error in object 'user' on field 'username': rejected value []; codes [NotEmpty.user.username,NotEmpty.username,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.username,username]; arguments []; default message [username]]; default message [用户名不能为空！]
Field error in object 'user' on field 'password': rejected value []; codes [NotEmpty.user.password,NotEmpty.password,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.password,password]; arguments []; default message [password]]; default message [密码不能为空！]
    at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:115) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:158) [spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128) [spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) [spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) [spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) [spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) [spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) [spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) [spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) [spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) [spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:661) [servlet-api.jar:?]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) [spring-webmvc-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) [servlet-api.jar:?]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) [catalina.jar:8.5.24]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.24]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-websocket.jar:8.5.24]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.24]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.24]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) [spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.24]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.24]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) [catalina.jar:8.5.24]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [catalina.jar:8.5.24]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504) [catalina.jar:8.5.24]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [catalina.jar:8.5.24]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [catalina.jar:8.5.24]
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650) [catalina.jar:8.5.24]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [catalina.jar:8.5.24]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [catalina.jar:8.5.24]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-coyote.jar:8.5.24]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-coyote.jar:8.5.24]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790) [tomcat-coyote.jar:8.5.24]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459) [tomcat-coyote.jar:8.5.24]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-coyote.jar:8.5.24]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_152]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_152]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.5.24]
    at java.lang.Thread.run(Thread.java:748) [?:1.8.0_152]
2017-12-24 19:02:21,261 DEBUG [http-nio-8080-exec-2] handler.AbstractHandlerExceptionResolver (AbstractHandlerExceptionResolver.java:133) - Resolving exception from handler [public java.lang.String me.auth.web.controller.UserController.login(me.auth.bean.User,org.springframework.ui.ModelMap,org.springframework.validation.BindingResult)]: org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 2 errors
Field error in object 'user' on field 'username': rejected value []; codes [NotEmpty.user.username,NotEmpty.username,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.username,username]; arguments []; default message [username]]; default message [用户名不能为空！]
Field error in object 'user' on field 'password': rejected value []; codes [NotEmpty.user.password,NotEmpty.password,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.password,password]; arguments []; default message [password]]; default message [密码不能为空！]
2017-12-24 19:02:21,263 DEBUG [http-nio-8080-exec-2] handler.AbstractHandlerExceptionResolver (AbstractHandlerExceptionResolver.java:133) - Resolving exception from handler [public java.lang.String me.auth.web.controller.UserController.login(me.auth.bean.User,org.springframework.ui.ModelMap,org.springframework.validation.BindingResult)]: org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 2 errors
Field error in object 'user' on field 'username': rejected value []; codes [NotEmpty.user.username,NotEmpty.username,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.username,username]; arguments []; default message [username]]; default message [用户名不能为空！]
Field error in object 'user' on field 'password': rejected value []; codes [NotEmpty.user.password,NotEmpty.password,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.password,password]; arguments []; default message [password]]; default message [密码不能为空！]
2017-12-24 19:02:21,264 DEBUG [http-nio-8080-exec-2] handler.AbstractHandlerExceptionResolver (AbstractHandlerExceptionResolver.java:133) - Resolving exception from handler [public java.lang.String me.auth.web.controller.UserController.login(me.auth.bean.User,org.springframework.ui.ModelMap,org.springframework.validation.BindingResult)]: org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 2 errors
Field error in object 'user' on field 'username': rejected value []; codes [NotEmpty.user.username,NotEmpty.username,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.username,username]; arguments []; default message [username]]; default message [用户名不能为空！]
Field error in object 'user' on field 'password': rejected value []; codes [NotEmpty.user.password,NotEmpty.password,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.password,password]; arguments []; default message [password]]; default message [密码不能为空！]
2017-12-24 19:02:21,264 DEBUG [http-nio-8080-exec-2] servlet.DispatcherServlet (DispatcherServlet.java:1048) - Null ModelAndView returned to DispatcherServlet with name 'spring-mvc': assuming HandlerAdapter completed request handling
2017-12-24 19:02:21,264 DEBUG [http-nio-8080-exec-2] servlet.FrameworkServlet (FrameworkServlet.java:1000) - Successfully completed request

这个bug出现的情况是将ModelMap或Model 形参放在了标记了@Validated注解的的形参后面，如：

public String login(
            @Validated User user,
            ModelMap modelMap,
            BindingResult bindingResult) {
    ...
}

解决办法是将ModelMap或Model形参放在@Validated注解的的形参前面，如：

public String login(
            ModelMap modelMap,
            @Validated User user,
            BindingResult bindingResult) {
    ...
}